About 20 people who were trapped on a roller coaster at Movie World on the Gold Coast have been safely evacuated.
Firefighters scaled the Arkham Asylum ride to free the passengers, who became stuck at the top about midday.
"We've been called to the scene for a vertical rescue," the Queensland Fire and Rescue Service said.
Firefighters used a cherry picker to rescue four people, while others were evacuated via a ladder platform set up by emergency services.
Queensland Ambulance said it had no reports of injuries but had set up a triage centre at the park.
Movie World general manager Greg Yong said there was a mechanical issue with a chain, but did not know exactly what went wrong.
They will look into whether heat played a role.
"Due to the time it will take to rectify this issue, we have decided to do an evacuation of the ride," Mr Yong said.
"This is a process we have drilled for fire services ... There were no injuries with any guests on board."
Mr Yong did not believe the ride would be closed for an "extended period of time" but said he could not give further details until a full analysis was undertaken.
The incident comes after four people were killed on a ride at Dreamworld, another Gold Coast theme park, late last year.